$ { {3} \times \left[\begin{array}{rrr}{3} & {1} & {0} \\ {-2} & {4} & {0}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{3}\times{3} & {3}\times{1} & {3}\times{0} \\ {3}\times{-2} & {3}\times{4} & {3}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{9} & {3} & {0} \\ {-6} & {12} & {0}\end{array}\right]}$